• 상하수도학회지
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• 제22권4호
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• pp.413-420
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• 2008

In order to utilize cinder melting slag as a filter media to control the quality of early rainwater, its environmental stability was verified by heavy metal elution experiment and improved by pre-treatment. Possibilities of improving its function as an absorbent was considered. Absorption characteristics of melting slag before and after the pre-treatment were analyzed by heavy metal equilibrium and stationary-phase column experiments, which in turn were analyzed by comparison experiment with activated carbon. As a result of heavy metal elution experiment, every metal item existed in a much lower amount than the criteria or was not detected, implying that there is no problem recycling it. Absorption equilibrium experiment showed that the time for pre-treatment melting slag to reach the equilibrium was reduced, while the absorbed amount was greatly increased. Stationary-phase column experiment assures us that the elimination rate was not changed much by influx rate, pH and the change in packing volume rate, indicating that this melting slag can be used not only as a filter media to control the quality of early rainwater but also in many areas of water-processing.

• 한국환경과학회지
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• 제20권8호
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• pp.997-1009
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• 2011

In order to estimate volume transport by upwelling for single artificial seamount, same shape and size of artificial seamount already deployed was applied to numerical experiment. The result showed that strong upwelling appeared at front while took place downwelling at rear. The strongest upwelling existed at the top of the artificial seamount. Volume transport by upwelling was computed as 785 m3/s. Column arrangement was applied to two artificial seamount in three cases; case 1) no clearance, case 2) sixty-five meters of clearance as half of artificial seamount's length, and case 3) hundred-thirty meters of clearance as an artificial seamount's length. All cases of column arrangements showed more upwelling volume transport than that of single seamount. Particularly, the case of no clearance calculated as 106% and appeared the most upwelling effect comparing to two other cases. Row arrangement was also applied to two artificial seamount in three cases; case 4) no clearance, case 5) forty meters of clearance as an artificial seamount's width, and case 6) eighty meters of clearance as twice of artificial seamount's width. Upwelling volume transport in case 4 increased 48% than the case of single seamount. Other two cases of 5 and 6 were estimated as 97% increased and more effective than case 4. According to the case experiments, column arrangements show more upwelling volume transport than that of row arrangements. In cases of column arrangements, with decreasing clearance between two seamount, the effect increases while showing maximum value at clearance zero. In cases of row arrangements, on the contrary, with decreasing clearance between two seamount, the effect decreases while showing minimum value at clearance zero. Since simple barotropic condition was considered for this study, further study is necessary by considering baroclinic condition to get close to reality. In conclusion, in deploying artificial seamount, optimal arrangement should be well designed to enhance primary and secondary productivity and to increase the diversity of species as well as reducing time and space.

• 디자인학연구
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• 제19권4호
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• pp.51-60
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• 2006

이제 스크린을 통한 독서는 아주 일상적인 일이 되었다. 특히 휴대폰, PDA, e북리더기 등 휴대형 정보기기의 등장으로 우리는 언제 어디서나 스크린을 통해 수많은 텍스트 기반 컨텐츠를 감상할 수 있게 되었다. 종래의 많은 연구는 스크린을 통한 독서가 종이에 비해 독서수행도가 저하되는 것으로 지적하고 있다. 더욱이 휴대형 정보기기에서는 스크린에 표시할 수 있는 텍스트의 행폭과 행수가 감소하므로 가독성은 더욱 악화될 수밖에 없다. 본 연구는 소형 스크린에서의 텍스트 가독성에 영향을 미치는 매개변수를 탐색하고 새로운 텍스트 레이아웃을 통해 가독성을 개선할 수 있는 방법을 제안하였다. 본 연구에서는 기존의 단조로운 직사각형 칼럼을 대각으로 분할하여 독서에서 리드미컬한 시선의 흐름을 유도할 수 있는 새로운 텍스트 레이아웃을 제안하고 직사각형 칼럼과 대각분할 칼럼에 대한 비교실험을 실시하였다. 그 결과 독서에 대한 주관적 만족도와 문장이해도 차원에서 양자 간에 유의한 차이가 발견되지 않았지만, $4000mm^2$와 $8000mm^2$크기의 소형 스크린에서는 대각분할 칼럼에서의 독서속도가 각각 18.9%, 34.0%향상되었음을 확인할 수 있었다. 대각분할 칼럼에서의 획기적인 독서수행도 개선의 원인을 보다 세밀하게 분석하기 위해 $4000mm^2$크기/3:1비례 화면의 조건에서 대각분할 칼럼을 구성하는 좌삼각 칼럼과 우삼각 칼럼의 독서수행도 비교실험을 실시하였다. 실험결과 직사각형 칼럼과 비교하였을 때 좌삼각 칼럼의 경우 21.1%, 우삼각 칼럼의 경우 67.6% 만큼 독서속도가 향상되었음을 확인할 수 있었다. 결국 우삼각 칼럼에서의 독서속도 향상이 대각분할 전체의 독서속도 향상에 크게 기여하고 있음을 알 수 있었다. 본 연구는 소형 스크린에서 대각분할이 독서수행도를 획기적으로 개선할 수 있음을 확인할 수 있었고 이는 소형 모바일 정보기기의 텍스트 레이아웃 디자인에 충분히 활용 가능할 것으로 기대된다.

• 대한환경공학회지
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• 제22권11호
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• pp.2007-2016
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• 2000

Kaolin clay 토양을 $Sr^{2+}$로 오염시킨 후 동전기적 방법으로 수일간 토양제염실험을 수행했다. 첫 번째 실험으로, 컬럼 내의 전기장을 높이기 위해 전해물질로 NaCl용액을 사용하였다. 토양제염결과 0.8일 경과 후 토양컬럼의 음극쪽에서의 pH는 초기의 4.0으로부터 약 11.7로 상승하면서 음극쪽 토양컬럼에서는 $Sr(OH)_2$가 형성되기 시작했다. 6.7일 동안의 실험결과 토양컬럼 14cm지점에 앞에서 이동된 $Sr^{2+}$들이 침전을 형성하며 계속 쌓이고 거의 이동되지 않기 때문에 제염효율은 32%에 불과했다. 두번째 실험으로, pH의 상승을 억제하기 위해 토양컬럼내에 초산완충액을 넣고, 음극저수조에는 0.1 M $CH_3COOH$을 연속적으로 주입했다. 컬럼의 14cm 뒤쪽 부분의 pH는 초기에는 4.0이었으나 실험이 끝나는 3.8일까지는 약 6.0으로 상승하여 컬럼 내에 $Sr(OH)_2$는 형성되지 않았다. 토양제염실험 결과 0.6일 후에는 토양컬럼 내의 초기 총농도의 21%가 제염되었고, 0.9일 후에는 33%가 제염되었다. 또한 1.6일 경과 후에는 84%가 제염되었고, 2.5일 후에는 92%, 그리고 3.8일 후에는 97%가 제염되었다. 또한 개발된 모델에 의해 계산된 토양컬럼 내의 잔류농도와 토양제염실험 후에 측정한 잔류농도는 상당히 일치했다.

• 한국지진공학회논문집
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• 제26권2호
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• pp.83-93
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• 2022

In this study, to verify the structural performance of the Composite Joint System (CJS) hybrid structural model, a cyclic load test was performed and evaluated and verified through the test. To verify the structural performance of the CJS hybrid structural systems' joint and evaluate the seismic performance, four three-dimensional real-size specimens were developed with three internal beam-column specimens and one external beam-column specimen. The three interior column specimens were classified by different methods of joining the upper column and lower column, and the same bonding method as the primary specimen was used for the exterior column. The structural performances in terms of drift, strength, and energy dissipation capacity were analyzed and compared based on the experimental results. From the displacement-based loading experiment, all specimens showed a lateral drift of 4.0% without any significant strength drop and stable energy dissipation capacity.

• Environmental Engineering Research
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• 제14권3호
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• pp.164-169
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• 2009

A powder form of aluminum (hydr)oxides is not suitable in wastewater treatment/filtration systems because of low hydraulic conductivity and large sludge production. In this study, aluminum (hydr)oxide-coated sand (AOCS) was used to remove phosphate from aqueous solution. The properties of AOCS were analyzed using a scanning electron microscopy (SEM) combined with an energy dispersive X-ray spectrometer (EDS) and an X-ray diffractometer (XRD). Kinetic batch, equilibrium batch, and closed-loop column experiments were performed to examine the adsorption of phosphate to AOCS. The XRD pattern indicated that the powder form of aluminum (hydr)oxides coated on AOCS was similar to a low crystalline boehmite. Kinetic batch experiments demonstrated that P adsorption to AOCS reached equilibrium after 24 h of reaction time. The kinetic sorption data were described well by the pseudo second-order kinetic sorption model, which determined the amount of P adsorbed at equilibrium ($q_e$ = 0.118 mg/g) and the pseudo second-order velocity constant (k = 0.0036 g/mg/h) at initial P concentration of 25 mg/L. The equilibrium batch data were fitted well to the Freundlich isotherm model, which quantified the distribution coefficient ($K_F$ = 0.083 L/g), and the Freundlich constant (1/n = 0.339). The closed-loop column experiments showed that the phosphate removal percent decreased from 89.1 to 41.9% with increasing initial pH from 4.82 to 9.53. The adsorption capacity determined from the closed-loop experiment was 0.239 mg/g at initial pH 7.0, which is about two times greater than that ($q_e$ = 0.118 mg/g) from the kinetic batch experiment at the same condition.

• 대한토목학회논문집
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• 제32권1B호
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• pp.85-91
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• 2012

영가철을 이용한 투수성 반응벽체는 지하수를 처리하는 원위치정화기술로 국내외적으로 연구가 활발히 진행되고 있다. 본 연구는 기존 영가철을 이용한 투수성 반응벽에 직류전원을 공급하여 효율이 향상된 TCE 처리기술 개발을 목적으로 하였다. 주문진규사로만 충진한 컨트롤컬럼, 영가철과 주문진규사로 충진한 영가철컬럼(영가철:주문진규사 = 1:2(v/v)) 그리고 영가철 컬럼에 직류전원을 공급한 복극전기분해컬럼, 이 세 컬럼의 운전을 통해 TCE 분해효율을 비교하였다. 실험 결과, 영가철를 충진하고 직류전원을 공급한 복극전기분해컬럼이 영가철만을 사용한 컬럼에 비해 높은 TCE의 환원효율을 나타내었다. 이는 영가철 입자가 미세전극으로 작용하여 전자의 이동을 촉진시킨 것에 기인한 것으로 보인다. 따라서 영가철이 반응매질로서의 역할만 할 때보다 반응매질의 역할과 동시에 전극으로서 작용했을 때, TCE 분해효율이 더 높게 나타났음을 알 수 있었다.

• Steel and Composite Structures
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• 제28권5호
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• pp.641-653
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• 2018

This paper presents experiment and bearing capacity analyses of steel dual-lintel column (SDC) joints in Chinese traditional style buildings. Two SDC interior joints and two SDC exterior joints, which consisted of dual box-section lintels, circular column and square column, were designed and tested under low cyclic loading. The force transferring mechanisms at the panel zone of SDC joints were proposed. And also, the load-strain curves at the panel zone, failure modes, hysteretic loops and skeleton curves of the joints were analyzed. It is shown that the typical failure modes of the joints are shear buckling at bottom panel zone, bending failure at middle panel zone, welds fracturing at the panel zone, and tension failure of base metal in the heat-affected zone of the joints. The ultimate bearing capacity of SDC joints appears to decrease with the increment of axial compression ratio. However, the bearing capacities of exterior joints are lower than those of interior joints at the same axial compression ratio. In order to predict the formulas of the bending capacity at the middle panel zone and the shear capacity at the bottom panel zone, the calculation model and the stress state of the element at the panel zone of SDC joints were studied. As the calculated values showed good agreements with the test results, the proposed formulas can be reliably applied to the analysis and design of SDC joints in Chinese traditional style buildings.

• 한국강구조학회 논문집
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• 제27권3호
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• pp.289-298
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• 2015

CFT 구조는 각형이나 원형강관에 콘크리트가 충전된 구조로서, 강관은 콘크리트를 구속하고 콘크리트는 강관의 좌굴을 방지함으로써 부재의 강성 및 강도를 증가시킬 수 있다. 이에 본 연구는 관통 다이아프램 충전개구부 형상이 각형CFT 기둥-보 접합부의 내력에 미치는 영향을 실험을 통해 확인한 후, 유한요소해석을 수행하여 실험 결과와 비교 검증했다. 이로써 각형CFT 기둥-보 접합부의 내력은 관통 다이아프램의 개구부 면적이 같을 경우 그 형상에 크게 영향을 받지 않으며, 관통 다이아프램과 보 플랜지의 접합부분 형상 및 치수가 동일하면, 보에 발생한 휨응력이 다이아프램을 통해 기둥으로 전달되고 있음을 확인하였다.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 2010년도 춘계학술논문발표회 논문집
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• pp.389-394
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• 2010

A concrete filled square steel tube (CFT) is composed of the external steel material, which its strength is reduced in fire due to sudden temperature increase, and the internal concrete with high thermal capacity that can ensure the fire resistance performance of the structure. Therefore, research about the influence factors of the structural performance of CFT column is required in order to apply CFT column to a fire resisting structure, and additional research about influence for each condition is also necessary. Among the influence factors, the boundary condition between column and beam is important structurally, and it is one of the major factors that determine overall fire resisting performance. This study performed a fire experiment under loading in order to analyse the influences of CFT column to the boundary condition. As the results of the experiment, fire resistance time of 106 minutes was ensured for the clamped-end condition but 89 minutes for the hinge-end condition in case of the 360 cross section. And, fire resistance time of 113 minutes was ensured for the clamped-end condition but 78 minutes for the hinge-end condition in case of the 280 cross section. The difference in the fire resistance performance according to changes in the boundary conditions showed a tendency that larger change effect on the fire resistance performance was derived from smaller cross section area.